Ministers are pressing ahead with the controversial reform of public sector pensions ahead of a strike on Thursday 10 May by tens of thousands of workers.

A public service pensions bill was included in the Queen's speech, despite continued opposition from unions who say the changes mean millions of workers will have to "work longer, pay more and get less" at retirement.

Plans for a flat-rate state pension initially worth about £140 a week also featured in the programme of measures, as part of a shake-up that will bring forward an increase in the state pension age to 67 between 2026 and 2028.

The government said the planned changes to public sector pensions would establish a common framework across the different schemes, adding: "The changes would also ensure provision is sustainable, and that costs and benefits between employers, workers and other taxpayers are balanced more fairly."

More than 1 million workers took part in walkouts in November 2011 in protest at the reforms, which typically include a rise in contributions and an increase in the retirement age, following on from changes that have already taken effect to the way the pensions of teachers and many other professions are paid out.

Civil servants, lecturers, health visitors, Ministry of Defence staff, immigration officers and off-duty police officers will be among those striking and taking part in other forms of protest on Thursday.

Bob Crow, leader of the National Union of Rail, Maritime and Transport Workers, said: "We will be sending the clearest message to the government that we will defend our pensions to the hilt, and the demand that our members should work longer, pay more and get less will be thrown back in the faces of this government of millionaire public schoolboys.

"The hammering the Con-Dems took in the polls last week should serve as a wake-up call from working men and women that we will not roll over and take the hit."

Meanwhile, under the pensions bill the basic state pension, currently worth up to £107.45 a week, and state second pension (also known as S2P and formerly known as Serps), will be replaced by a single scheme which the government says will cost no more than the existing system.

The reforms follow concerns that people are not being encouraged to save enough for their old age as they are being put off by an overly complex system.

The Treasury had originally been concerned about the affordability of the reforms, but the government has said the "single tier" pension will be introduced "early in the next parliament", in about 2016.

Critics say it will mean that while those on low incomes who have made small or no contributions to the S2P will benefit from a higher pension than they could hope for now, in future people who earn higher salaries and contribute more to the S2P will lose out.

Britain's biggest pensioner organisation, the National Pensioners Convention, has pointed out that someone retiring today with a 30-year contribution record would already get a combined pension of about £150 a week.

The government says that when it comes to those planning to retire in the next few years, "accrued rights will be honoured … Whatever you have accrued over and above the £140, you will get that".

The details of how the transition will work are expected to be included in a white paper due in the next few weeks. Final decisions on the detailed implementation will be taken at the next spending review.